System and method for controlling an engine cooling fan

ABSTRACT

A system and method of operating a cooling system for a vehicle engine, wherein one or more motors are operable to rotate one or more fans. Each of the one or more motors is controlled by a motor controller associated with the motor, in response to a control signal received from a system controller and an enable signal received from the vehicle. The motor controller operates the motor at a speed based upon the control signal if the control signal is received, and operates the motor at a predetermined speed if the control signal is not received but the enable signal is received.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Divisional of U.S. patent application Ser.No. 14/139,078, filed Dec. 23, 2013, the entire contents of which arehereby incorporated by reference.

BACKGROUND

The present invention relates to a system and method for controlling oneor more fans configured to promote the cooling of an internal combustionengine.

Engine cooling systems typically include one or more heat exchangers(e.g., a radiator, a charge-air cooler, an oil cooler, etc.) and one ormore fans. The heat exchanger(s) and the fan(s) are configured to coolthe internal combustion engine and/or fluids associated with theinternal combustion engine.

SUMMARY

In some embodiments, the invention provides a cooling system for avehicle engine, wherein the cooling system is powered by a power sourceand includes a heat exchanger, a system controller, a motor electricallyconnected to the power source, a fan driven by the motor, and a motorcontroller. The motor controller is electrically connected to the systemcontroller, the power source and the motor, and is configured to receivepower from the power source, receive an enable signal from the vehicle,and to receive a control signal from the system controller. Uponreceiving the control signal, the motor controller operates the motor ata first speed based on the control signal. If the first control signalis not received, but the enable signal is received, the motor controlleroperates the motor at a second speed.

Some embodiments of the present invention provide a method of operatinga cooling system for a vehicle engine, wherein the cooling systemincludes a motor operable to rotate a fan. The method includesdetermining if a control signal has been received; operating the motorto rotate the fan at a first speed if the control signal has beenreceived, wherein the first speed is based on the control signal; andoperating the motor to rotate the fan at a second speed if the controlsignal has not been received.

Other aspects of the invention will become apparent by consideration ofthe detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a cooling system for a vehicle engineaccording to one embodiment of the invention.

FIG. 2 is a block diagram of a control system of the cooling system ofFIG. 1.

FIG. 3 is a flow chart illustrating a process of the cooling system ofFIG. 1.

FIG. 4 is perspective view of certain portions of the cooling system ofFIG. 1.

DETAILED DESCRIPTION

Before any embodiments of the invention are explained in detail, it isto be understood that the invention is not limited in its application tothe details of construction and the arrangement of components set forthin the following description or illustrated in the accompanyingdrawings. The invention is capable of other embodiments and of beingpracticed or of being carried out in various ways.

FIG. 1 is a perspective view of a cooling system 100 for use in aninternal combustion engine driven vehicle. The cooling system 100includes an assembly of heat exchangers 105 and motor and fan assemblies110. The cooling system 100 cools, for example, an internal combustionengine such as a vehicle engine (not shown).

The assembly of heat exchangers 105 is shown in greater detail in FIG.4, and includes a radiator 106 and a charge-air cooler 107. The radiator106 cools a liquid engine coolant that is pumped through a coolingjacket of the internal combustion engine in order to regulate the enginetemperature. The illustrated radiator 106 includes an inlet 115, anoutlet 120, and a core 125. In operation, warm liquid enters theradiator 106 via the inlet 115. The warm liquid passes through a seriesof tubes of the core 125. As the liquid passes through the core 125,heat from the liquid is rejected to air passing over the tubes and theliquid is cooled. The cooled liquid exits the radiator 106 via theoutlet 120. The charge-air cooler cools a flow of pressurized combustionair for the internal combustion engine. The illustrated charge aircooler includes an inlet 116, an outlet 121, and a core 126. Inoperation, hot charge-air enters the charge-air cooler via the inlet116. The hot charge-air passes through a series of tubes of the core126. As the charge-air passes through the core 126, heat from thecharge-air is rejected to air passing over the tubes and the charge-airis cooled. In some embodiments, additional heat exchangers such as, forexample, oil coolers, transmission coolers, refrigerant condensers, andthe like can also be included within the assembly of heat exchangers105.

The motor and fan assemblies 110 circulate air through the assembly ofheat exchanger 105 (for example the core 125 of the radiator 106 and thecore 126 of the charge-air cooler 107) to provide the necessary coolingair. The assemblies 110 each include a fan 130, a motor 135, and a motorcontroller 140. Although shown in the illustrated embodiment asincluding eight motor and fan assemblies 110, the cooling system 100 mayhave one or any other number of motor and fan assemblies 110. In someembodiments, a subset of the fan assemblies 110 can be dedicated to eachof the heat exchangers within the assembly of heat exchanger 105, sothat the rate of cooling within each of the heat exchangers can becontrolled independently of the rate of cooling of the other heatexchangers. For ease of description, only one of the motor and fanassemblies 110 is described hereinafter, although it will be understoodthat the description can apply to any number of the other motor and fanassemblies 110, if present.

The motor 135 rotates the fan 130. The motor 135 is an electrical motor,such as but not limited to a direct-current motor operable at variablespeeds. In some embodiments, the motor 135 is a brushless direct-current(BLDC) motor. In other embodiments, the motor 135 can be a variety ofother types of motors, including but not limited to a brush DC motor, astepper motor, a synchronous motor, or other direct-current oralternating-current motors.

The motor controller 140 operates the motor 135. The motor controller140 includes a plurality of electrical and electronic components thatprovide power, operational control, and protection to the components andmodules within the motor controller 140 and/or the motor 135. Forexample, the motor controller 140 includes, among other things, aprocessing unit (e.g., a microprocessor, a microcontroller, or anothersuitable programmable device) and a memory unit. In some embodiments,the motor controller 140 is implemented partially or entirely on asemiconductor (e.g., a field-programmable gate array [“FPGA”]semiconductor) chip, such as a chip developed through a registertransfer level (“RTL”) design process. In one example, upon receiving acontrol signal, the motor controller 140 controls and/or operates theswitching of a plurality of electronic switches (e.g., FETs), in orderto selectively drive the motor 135 at a speed. In some embodiments, themotor controller 140 and the motor 135 form a single unit. In otherembodiments, the motor controller 140 and the motor 135 are individualcomponents of the motor and fan assembly 110.

The motor controller 140 includes a plurality of connections (e.g.,inputs, outputs, input/outputs, etc.). In some embodiments, theplurality of connections include a control signal connection, a batterypositive connection, a battery negative (e.g., ground) connection, anenable signal connection, and a diagnostic connection.

The cooling system 100 further includes a system controller 150. Thesystem controller 150 is in communication with the motor controllers 140through at least some of the plurality of connections of each of themotor controllers 140. For example, the system controller 150 and amotor controller 140 can communicate along a control signal connectionand a diagnostic connection.

FIG. 2 is a block diagram illustrating a control system 200 of thecooling system 100. The control system 200 includes the systemcontroller 150. The system controller 150 is electrically and/orcommunicatively connected to a variety of modules or components of thecontrol system 200 and cooling system 100. For example, the illustratedsystem controller 150 is connected to the motor controller 140, a powersupply module 210, a communications module 215, and one or more sensors220. The system controller 150 can include combinations of hardware andsoftware that are operable to, among other things, control the operationof the cooling system 100, and specifically, the motor and fan assembly110 of the cooling system 100.

The system controller 150 can include a plurality of electrical andelectronic components that provide power, operational control, andprotection to the components and modules within the system controller150 and/or the cooling system 100. For example, the system controller150 includes, among other things, a processing unit 225 (e.g., amicroprocessor, a microcontroller, or another suitable programmabledevice) and a memory 230. In some embodiments, the system controller 150is implemented partially or entirely on a semiconductor (e.g., afield-programmable gate array [“FPGA”] semiconductor) chip, such as achip developed through a register transfer level (“RTL”) design process.

The memory 230 includes, for example, a program storage area and a datastorage area. The program storage area and the data storage area caninclude combinations of different types of memory, such as read-onlymemory (“ROM”), random access memory (“RAM”) (e.g., dynamic RAM[“DRAM”], synchronous DRAM [“SDRAM”], etc.), electrically erasableprogrammable read-only memory (“EEPROM”), flash memory, a hard disk, anSD card, or other suitable magnetic, optical, physical, or electronicmemory devices. The illustrated processing unit 225 is connected to thememory 230 and executes software instructions that are capable of beingstored in a RAM of the memory 230 (e.g., during execution), a ROM of thememory 230 (e.g., on a generally permanent basis), or anothernon-transitory computer readable medium such as another memory or adisc. Software included in some implementations of the cooling system100 can be stored in the memory 230 of the system controller 150. Thesoftware can include, for example, firmware, one or more applications,program data, filters, rules, one or more program modules, and otherexecutable instructions. The system controller 150 is configured toretrieve from memory and execute, among other things, instructionsrelated to the control processes and methods described herein. In otherconstructions, the controller 150 includes additional, fewer, ordifferent components.

The illustrated power supply module 210 receives power from a powersupply and outputs a nominal DC voltage to the system controller 150 andoptionally to other components or modules of the cooling system 100. Insome embodiments, the power supply module 240 may receive power from oneor more batteries or battery packs, and may receive that power by way ofa vehicle ignition system. In some embodiments, the one or morebatteries or battery packs further provide power to a vehicle andcomponents of the vehicle. In other embodiments, the power supply module210 may receive power from other grid-independent power sources (e.g., asolar panel, etc.).

In the illustrated embodiment, a vehicle ignition system 240 iselectrically connected to and outputs a nominal DC voltage (e.g., 5V,10V, 20V, 24V, etc.) to the motor controller 140. In some embodiments,the voltage output by the vehicle ignition system 240 functions as anenable signal. In some embodiments, the vehicle ignition system 240 iselectrically connected to the motor controller 140 at a vehicle ignitionconnection of the motor controller 140. The motor controller 140 is alsoelectrically connected to one or more batteries 235 via a batterypositive connection and a battery negative (e.g., ground) connection. Insome embodiments the batteries 235 can be replaced by an alternate powersource.

The communications module 215 provides analog and/or digitalcommunications from the system controller 150 to outside devices. Insome embodiments, the communications module 215 outputs diagnosticinformation concerning the controller 150 and/or other components of thecooling system 100. The communications module 215 may include an outputdriver in the form of a digital driver such as SAE J1939 or CAN bus forcommunicating directly to the vehicle's data bus, or the communicationsmodule 215 may generate another suitable analog or digital signaldepending on the needs of the specific application.

The one or more sensors 220 sense any number of a variety ofcharacteristics of the cooling system 100 and the internal combustionengine. For example, the one or more sensors 220 can sensecharacteristics of the motor 135, including but not limited torotational speed, torque, power, voltage, current, and temperature. Insome embodiments, the one or more sensors 220 include one or moretemperature sensors configured to sense, for example, a temperature ofthe cooling system 100, a temperature of the radiator 106 or portions ofthe radiator 106, a temperature of the charge-air cooler 107 or portionsof the charge-air cooler 107, and/or a temperature of the internalcombustion engine being cooled.

In operation, the system controller 150 outputs a control signal to themotor controller 140. The motor controller 140 receives the controlsignal and operates the motor 135 based on the control signal. In someembodiments, the control signal is a pulse-width modulated signal. Thepulse-width modulated signal can have a duty cycle (e.g., 10%, 50%,100%, etc.). In some embodiments, the duty cycle corresponds to anoperating speed of the motor 135 (e.g., 10% of full speed, 50% of fullspeed, 100% of full speed, etc.).

In some embodiments, during a standby mode the controller 150 willoutput a standby control signal (e.g., a control signal having a 3% dutycycle) having a standby speed. Thus, during the standby mode, the motorcontroller 140 will receive the standby control signal from thecontroller 150 and operate the motor 135 at the predetermined standbyspeed based on the standby control signal. In some such embodiments thestandby speed is zero.

During operation, the system controller 150 receives one or more sensedcharacteristics from the one or more sensors 220. The system controller150 may output a different control signal to the motor controller 140based on the one or more sensed characteristics. For example, the systemcontroller 150 may receive a temperature of the cooling system 100 orvarious components of the cooling system 100. The system controller 150may increase, decrease, or maintain the operating speed of the motor 135by outputting a control signal based on the received temperature(s). Thesystem controller 150 may output a first control signal to a first motorcontroller 140, and a second control signal different in value from thefirst control signal to a second motor controller 140.

If during operation the motor controller 140 receives an enable signalfrom the vehicle ignition system 240 but does not receive a controlsignal (e.g., a normal control signal or a standby control signal) fromthe system controller 150, or in some embodiments receives a controlsignal having a 0% duty cycle, the motor controller 140 waits for apredetermined time (e.g., three-seconds, five-seconds, ten-seconds,etc.) and then operates the motor 135 at a predetermined speed (e.g., adefault speed of approximately 3750 RPM). In alternative embodiments,the motor controller 140 does not wait for a predetermined time (afterfailing to receive a control signal or a control signal having a 0% dutycycle) to operate the motor 135 in such a manner, and insteadimmediately operates the motor 135 at the predetermined speed.

Chart 1 below illustrates an example operation of the cooling system100, including whether the motor and fan assembly 110 is receiving acontrol signal from the system controller 150 and/or is receiving acontrol signal from the vehicle ignition system 240, and thecorresponding operation of the motor and fan assembly 110. In operation,when the motor and fan assembly 110 does not receive either of a controlsignal from the system controller 150 and an enable signal from thevehicle ignition system 240, the motor and fan assembly 110 operates themotor 135 at zero RPMs. If the motor and fan assembly 110 does notreceive a control signal from the system controller 150, but receives anenable signal from the vehicle ignition system 240, the motor and fanassembly 110 operates the motor 135 at a predetermined speed (e.g., 3750RPMs). If the motor and fan assembly 110 receives a control signal fromthe system controller 150 but does not receive an enable signal from thevehicle ignition system 240, the motor and fan assembly 110 operates themotor 135 at a speed according to the control signal from the systemcontroller 150. Such an operation may occur if there is a failure of thevehicle ignition system 240, or an issue with the wiring between thevehicle ignition system 240 and the motor and fan assembly 110. If themotor and fan assembly 110 receives a control signal from the systemcontroller 150 and receives an enable signal from the vehicle ignitionsystem 240, the motor and fan assembly 110 operates the motor 135 at aspeed according to the control signal from the controller 150.

Enable Signal from Control Signal from Vehicle Ignition Motor & FanAssembly system Controller 150 System 240 110 Status OFF OFF OFF OFF ONOperates at predetermined speed (e.g., 3750 RPMs). ON OFF Operates atspeed according to control signal. ON ON Operates at speed according tocontrol signal.

In embodiments having more than one motor and fan assembly 110, such asthe illustrated embodiment, the system controller 150 may be operable tooutput a plurality of control signals, each having different dutycycles, to the plurality of motor controllers 140. Thus, the systemcontroller 150 can be operable to control the various motor and fanassemblies 110 at different speeds, or one or more motor and fanassemblies 110 at a standby speed. For example, the system controller150 may operate a first motor and fan assembly 110 at a first speed, asecond motor and fan assembly 110 at a second speed, and a third motorand fan assembly 110 at a standby speed.

FIG. 3 illustrates an operation 300 of the cooling system 100 accordingto an embodiment of the present invention. The operation 300 begins bythe vehicle turning on (Step 305). The system controller 150 receivespower from a power source (Step 310). The system controller 150 receivesone or more sensed characteristics (Step 315), and outputs a controlsignal based on at least the one or more sensed characteristics (Step320). The motor controller 140 determines if the control signal has beenreceived (Step 325). If the control signal has been received, the motorcontroller 140 operates the motor 135 based on the control signal (Step330). If the control signal has not been received, the motor controller140 determines is an enable signal has been received (step 350). If anenable signal has been received, the motor controller 140 waits for apredetermined time period (Step 335). The motor controller 140determines if the control signal has been received during thepredetermined time period (Step 340). If the motor controller 140 hasreceived the control signal within the predetermined time period, theoperation 300 proceeds to Step 330. If the motor controller 150 has notreceived the control signal within the predetermined time period, themotor controller 140 operates the motor 135 at a predetermined operatingspeed (e.g., the default speed) (Step 345). If during step 350 an enablesignal has not been received, then the motor controller 140 does notoperate the motor 135.

As one particular advantage of the above described operation, a failureof the system controller 150 does not result in a shut-down of thecooling system 100, provided that an enable signal from the vehicleignition system 240 is received by a motor controller 140. As a result,the vehicle would still be able to be driven to, for example, a garageor repair facility so that the system controller 150 could be replaced.The presence of an electrical connection between the vehicle ignitionsystem 240 and each of the motor controllers 140 is not, however,required for the operation of the cooling system 100 in the case of anon-faulty system controller 150, so that failure probabilities of thesystem do not increase by the addition of such a connection.

Thus, the invention provides, among other things, a system and methodfor controlling one or more fans configured to promote the cooling of aninternal combustion engine. Various features and advantages of theinvention are set forth in the following claims.

What is claimed is:
 1. A cooling system for a vehicle, the coolingsystem powered by a power source, the cooling system comprising: a heatexchanger; a system controller; a motor; a fan driven by the motor; anda motor controller electrically connected to the system controller, thepower source, and the motor, the motor controller configured to receivepower from the power source, receive an enable signal from the vehicle,and receive a control signal from the system controller, wherein uponreceiving the control signal, the motor controller operates the motor ata first speed based on the control signal; and wherein upon notreceiving the control signal but receiving the enable signal, the motorcontroller operates the motor at a second speed.
 2. The cooling systemof claim 1, wherein the enable signal is received from an ignitionsystem of the vehicle.
 3. The cooling system of claim 1, wherein themotor, the fan, and the motor controller are one of a plurality ofmotors, fans, and motor controllers, each of the plurality of motorcontroller individually receiving a control signal from the systemcontroller and an enable signal from the vehicle.
 4. The cooling systemof claim 1, wherein the motor waits a predetermined period of timebefore operating at the second speed.
 5. The cooling system of claim 1,wherein the system controller receives a sensed characteristic of atleast one of the cooling system and the vehicle engine, the controlsignal based at least in part on the sensed characteristic.
 6. Thecooling system of claim 5, wherein the sensed characteristic is atemperature.
 7. The cooling system of claim 1, wherein the controlsignal is a pulse-width modulated signal.
 8. A cooling system for avehicle, the cooling system powered by a power source, the coolingsystem comprising: a heat exchanger; a system controller; a motor; a fandriven by the motor; and a motor controller electrically connected tothe motor to drive the motor, the motor controller comprising: a controlsignal connection electrically connected to the system controller toreceive a control signal therefrom; a direct electrical connection tothe power source; and an enable signal connection separate from thedirect electrical connection to the power source and electricallyconnected to an ignition system of the vehicle to receive an enablesignal therefrom.
 9. The cooling system of claim 8, wherein the powersource comprises one or more batteries.
 10. The cooling system of claim9, wherein the direct electrical connection comprises a battery positiveconnection and a battery negative connection.
 11. The cooling system ofclaim 8, wherein the enable signal connection is an indirect connectionto the power source by way of the ignition system in at least someoperating conditions.
 12. The cooling system of claim 8, wherein themotor controller is operable to provide electrical power to the motor inorder to drive the fan at a non-zero speed under a first operatingcondition, the first operating condition comprising: receiving theenable signal through the enable signal connection; and not receiving acontrol signal through the control signal connection for at least apredetermined period of time.
 13. The cooling system of claim 12,wherein the predetermined period of time is between three and eightseconds.
 14. The cooling system of claim 12, wherein the motorcontroller is operable to provide electrical power to the motor in orderto drive the fan at a non-zero speed under a second operating condition,the second operating condition comprising: receiving the enable signalthrough the enable signal connection; and receiving a control signalthrough the control signal connection with a duty cycle less than athreshold duty cycle for at least a predetermined period of time. 15.The cooling system of claim 14, wherein the predetermined period of timeis between three and eight seconds.
 16. The cooling system of claim 14,wherein the threshold duty cycle is a 3% duty cycle.
 17. A coolingsystem for a vehicle, the cooling system powered by a power source, thecooling system comprising: a heat exchanger; a system controller; amotor; a fan driven by the motor; and a motor controller having a firstelectrical connection to the system controller to receive a controlsignal therefrom under at least some operating conditions, a secondelectrical connection to an ignition system of the vehicle to receive anenable signal therefrom under at least some operating conditions, athird electrical connection to the power source, and a fourth electricalconnection to the motor, wherein the motor controller is operable todrive the motor at a non-zero speed by supplying electrical power fromthe power source to the motor in response to receiving the enable signalwhile simultaneously not receiving the control signal for at least apredetermined period of time.
 18. The cooling system of claim 17,wherein the enable signal connection is an indirect connection to thepower source by way of the ignition system.
 19. The cooling system ofclaim 17, wherein third electrical connection comprises a directconnection to one or more batteries of the vehicle.
 20. The coolingsystem of claim 17, wherein the predetermined period of time is at leastthree seconds in duration.